Zero-profile implant system versus novel plate systems after ACDF for comparison of sagittal balance parameters and clinical efficacy analysis.

BACKGROUND: The zero-profile implant system (Zero-P) and conventional plates have been widely used in anterior cervical discectomy and fusion (ACDF) to treat cervical spondylosis. The purpose of this study was to compare the effects of the application of Zero-P and new conventional plates (ZEVO, Skyline) in ACDF on the sagittal imaging parameters of cervical spondylosis patients and to analyze their clinical efficacy. METHODS: We conducted a retrospective study on 119 cervical spondylosis patients from January 2018 to December 2021, comparing outcomes between those receiving the Zero-P device (n = 63) and those receiving a novel conventional plate (n = 56, including 46 ZEVO and 10 Skyline plates) through ACDF. Cervical sagittal alignment was assessed pre- and postoperatively via lateral radiographs. The Japanese Orthopedic Association (JOA), Neck Disability Index (NDI), and visual analog scale (VAS) scores were recorded at baseline, after surgery, and at the 2-year follow-up to evaluate patient recovery and intervention success. RESULTS: There were significant differences in the postoperative C0-C2 Cobb angle and postoperative sagittal segmental angle (SSA) between patients in the novel conventional plate group and those in the Zero-P group (P < 0.05). Postoperatively, there were significant changes in the C2‒C7 Cobb angle, C0‒C2 Cobb angle, SSA, and average surgical disc height (ASDH) compared to the preoperative values in both patient groups (P < 0.05). Dysphagia in the immediate postoperative period was lower in the Zero-P group than in the new conventional plate group (0% in the Zero-P group, 7.14% in the novel conventional plate group, P = 0.046), and the symptoms disappeared within 2 years in both groups. There was no statistically significant difference between the two groups in terms of complications of adjacent spondylolisthesis (ASD) at 2 years postoperatively (3.17% in the Zero-P group, 8.93% in the novel conventional plate group; P = 0.252). According to the subgroup analysis, there were significant differences in the postoperative C2‒C7 Cobb angle, C0‒C2 Cobb angle, T1 slope, and ASDH between the ZEVO group and the Skyline group (P < 0.05). Compared with the preoperative scores, the JOA, NDI, and VAS scores of all groups significantly improved at the 2-year follow-up (P < 0.01). According to the subgroup analysis, the immediate postoperative NDI and VAS scores of the ZEVO group were significantly better than those of the Skyline group (P < 0.05). CONCLUSION: In ACDF, both novel conventional plates and Zero-P can improve sagittal parameters and related scale scores. Compared to the Zero-P plate, the novel conventional plate has a greater advantage in correcting the curvature of the surgical segment, but the Zero-P plate is less likely to produce postoperative dysphagia.

Comparison of the efficacy of ROI-C cage with Zero-P device in anterior cervical discectomy and fusion of cervical degenerative disc disease: a two-year follow-up study.

Background: This study aimed to compare the clinical outcomes of Zero-P and ROI-C devices applied to anterior cervical discectomy and fusion (ACDF) surgery of cervical degenerative disc disease (CDDD). Methods: From January 2020 and December 2020, 56 patients with CDDD who underwent ACDF using Zero-P or ROI-C were included in this retrospective study. The outcomes included visual analogue scale (VAS) score, Japanese Orthopedic Association (JOA) score, neck disability index (NDI) score, Cobb angle, dysphagia, and bone fusion rate. Dysphagia was assessed using the Bazaz grading system. The comparison of outcomes between the two groups was based on the 2-year follow-up time point, which was defined as the last follow-up visit. Results: The Zero-P group included 16 males and 14 females, with a mean age of 56.2 (range, 35-65) years. The ROI-C group included 11 males and 15 females, with a mean age of 57.4 (range, 36-67) years. There was no significant difference in gender and mean age between the two groups. There were no significant differences in VAS score, JOA score, NDI score, Cobb angle, dysphagia, and bone fusion rate between two groups at the last follow up visit. In the Zero-P group, the duration of surgeries involving C3-4 or C6-7 segments was significantly longer than those including C4-5 or C5-6 segments (135.0 ± 19.0 vs. 105.6 ± 17.5 min, P < 0.05). In surgeries involving C3-4 or C6-7 segments, the operation time of ROI-C was significantly shorter than that of Zero-P (106.5 ± 19.5 vs.112.2 ± 20.5 min, P < 0.05). There were no significant differences in the dysphagia or cage subsidence rates between the Zero-P and ROI-C groups (P > 0.05). The Cobb angle in the last follow-up visit in the Zero-P group (24.4 ± 4.5°) was significantly higher than that in the ROI-C group (18.1 ± 2.3°) (P < 0.05). Conclusions: ACDF using ROI-C device showed an efficacy similar to the Zero-P device, as well as a shorter operation time for surgeries involving C3-4 or C6-7 segments. However, ROI-C could cause more loss of Cobb angle over time, which could lead to uncomfortable symptoms.

Anterior cervical discectomy and fusion with a zero-profile VA spacer device: a clinical and radiological study with two-year follow-up.

STUDY DESIGN: A retrospective study. OBJECTIVE: The aim of this study was to compare clinical and radiological outcomes of the anterior cervical discectomy and fusion (ACDF) with a novel zero-profile variable-angle (Zero-P VA) spacer and a traditional poly-ether-ether-ketone (PEEK) cage and plate system in cases pertaining to cervical radiculopathy/myelopathy. There are two conventional types of ACDF procedures aimed at treating symptomatic cervical spondylosis. The first one involves an uninstrumented "stand-alone" approach utilizing bone graft/cage, while the second incorporates bone graft/cage in conjunction with a front plate positioned before the vertebral bodies. Both procedures have their own inherent advantages and disadvantages. The Zero-P VA spacer, however, represents a unique synthesis by amalgamating the advantages of both traditionally typical procedures. Notably, this spacer can potentially circumvent the issue related to prevertebral soft-tissue disturbance and reduce the occurrence of dysphagia. METHODS: Using our surgical database, the authors systematically conducted a retrospective analysis encompassing all patients who underwent single-level ACDF between January 2018 and January 2019, with a minimum two-year follow-up. Patients either received a Zero-P VA implant or PEEK cage coupled with plating. The Japanese Orthopedic Association (JOA) score and Visual Analogue Scale (VAS) for arm and neck pain were documented. Dysphagia was evaluated using the Eating Assessment Tool-10 (ETA-10). Additional parameters such as cervical alignment, fusion rate and the incidence of postoperative complications were assessed. RESULTS: According to the outcomes of the statistical analysis, there was no substantial disparity that emerged in the advancements observed in the JOA and VAS metrics between the two study cohorts. Noteworthy, however, the ETA-10 scores were statistically significantly reduced in the Zero-P VA group compared to the cage and plating group (p < 0.05). At the final follow-up, there were no statistically significant differences in the height of the operated segment, Cobb angle of the fused segment, C2-C7 Cobb angle and fusion rate between the two groups (p > 0.05). However, postoperative complications were slightly lower in patients with the Zero-P VA group (7.69%) as compared to the cage and plating group (16.67%). CONCLUSION: The clinical outcomes observed with the Zero-P VA spacer used for single-level ACDF were found to be satisfactory. The performance of this device is comparable or even superior to the traditional cage and plating method in preventing postoperative dysphagia and mitigating potential complications associated with the use of a plate.

Structural bases for the Charcot-Marie-Tooth disease induced by single amino acid substitutions of myelin protein zero.

Myelin protein zero (MPZ or P0) is a transmembrane protein which functions to glue membranes in peripheral myelin. Inter-membrane adhesion is mediated by homophilic interactions between the extracellular domains (ECDs) of MPZ. Single amino acid substitutions in an ECD cause demyelinating neuropathy, Charcot-Marie-Tooth disease (CMT), with unknown mechanisms. In this study, by using a novel assay system "nanomyelin," we revealed that a stacked-rings-like ECD-8-mer is responsible for membrane adhesion. Two inter-ECD interactions, cis and head-to-head, are essential to constituting the 8-mer and to gluing the membranes. This result was reinforced by the observation that the CMT-related N87H substitution at the cis interface abolished membrane-adhesion activity. In contrast, the CMT-related D32G and E68V variants retained membrane-stacking activity, whereas their thermal stability was lower than that of the WT. Reduced thermal stability may lead to impairment of the long-term stability of ECD and the layered membranes of myelin.

Biomechanical performance of the novel assembled uncovertebral joint fusion cage in single-level anterior cervical discectomy and fusion: A finite element analysis.

Introduction: Anterior cervical discectomy and fusion (ACDF) is widely accepted as the gold standard surgical procedure for treating cervical radiculopathy and myelopathy. However, there is concern about the low fusion rate in the early period after ACDF surgery using the Zero-P fusion cage. We creatively designed an assembled uncoupled joint fusion device to improve the fusion rate and solve the implantation difficulties. This study aimed to assess the biomechanical performance of the assembled uncovertebral joint fusion cage in single-level ACDF and compare it with the Zero-P device. Methods: A three-dimensional finite element (FE) of a healthy cervical spine (C2-C7) was constructed and validated. In the one-level surgery model, either an assembled uncovertebral joint fusion cage or a zero-profile device was implanted at the C5-C6 segment of the model. A pure moment of 1.0 Nm combined with a follower load of 75 N was imposed at C2 to determine flexion, extension, lateral bending, and axial rotation. The segmental range of motion (ROM), facet contact force (FCF), maximum intradiscal pressure (IDP), and screw-bone stress were determined and compared with those of the zero-profile device. Results: The results showed that the ROMs of the fused levels in both models were nearly zero, while the motions of the unfused segments were unevenly increased. The FCF at adjacent segments in the assembled uncovertebral joint fusion cage group was less than that that of the Zero-P group. The IDP at the adjacent segments and screw-bone stress were slightly higher in the assembled uncovertebral joint fusion cage group than in those of the Zero-P group. Stress on the cage was mainly concentrated on both sides of the wings, reaching 13.4-20.4 Mpa in the assembled uncovertebral joint fusion cage group. Conclusion: The assembled uncovertebral joint fusion cage provided strong immobilization, similar to the Zero-P device. When compared with the Zero-P group, the assembled uncovertebral joint fusion cage achieved similar resultant values regarding FCF, IDP, and screw-bone stress. Moreover, the assembled uncovertebral joint fusion cage effectively achieved early bone formation and fusion, probably due to proper stress distributions in the wings of both sides.

Is the Zero-P Spacer Suitable for 3-Level Anterior Cervical Discectomy and Fusion Surgery in Terms of Sagittal Alignment Reconstruction: A Comparison Study with Traditional Plate and Cage System.

The Zero-P spacer was primarily developed aiming to reduce the morbidity associated with the traditional anterior cervical plate. During the past decade, many authors have reported the use of Zero-P spacers for anterior cervical discectomy and fusion (ACDF) of one or two segments. Nevertheless, there is still a paucity of knowledge on the safety and feasibility of using Zero-P spacers for 3-level fixation. The objective of this study was to investigate the clinical and radiological outcomes, with a focus on the sagittal alignment reconstruction of 3-level ACDF surgery using Zero-P spacers versus those using a traditional plate and cage system. From Sep 2013 to Aug 2016, a total of 44 patients who received 3-level ACDF surgery due to cervical spondylotic myelopathy were recruited. The Zero-P spacer was used in 23 patients (group ZP) and the traditional plate and cage system in 21 (group PC). Clinical outcomes were analyzed by Neck Disability Index (NDI) and Japanese Orthopedic Association (JOA) scores, and dysphagia was evaluated using the Bazaz score. Radiological outcomes, including fusion rate, adjacent segment degeneration (ASD), and especially changes in cervical sagittal alignment, were analyzed. The NDI and JOA scores did not differ significantly between the two groups postoperatively (p > 0.05); however, there was significantly less dysphagia in patients using Zero-P spacers at the 3- and 6-month follow-up (p < 0.05). At the 24-month follow-up, the fusion rate and ASD were similar between the two groups (p > 0.05). Interestingly, patients using Zero-P spacers had a significantly lower postoperative C2-7 Cobb angle and fused segment Cobb angle, compared to those using a traditional plate and cage system (p < 0.05); meanwhile, the fused segment disc wedge was also found to be significantly smaller in patients using Zero-P spacers after surgery (p < 0.05). Moreover, we further divided patients into subgroups according to their cervical lordosis. In patients with a preoperative C2-7 Cobb angle ≤ 10°, significantly less cervical and local lordosis, as well as disc wedge, were seen in group ZP after surgery (p < 0.05), while in others with a preoperative C2-7 Cobb angle > 10°, no significant difference in postoperative changes of the cervical sagittal alignment was seen between group ZP and group PC (p > 0.05). Zero-P spacers used in 3-level ACDF surgery could provide equivalent clinical outcomes and a lower rate of postoperative dysphagia, compared to the traditional plate and cage system. However, our results showed that it was inferior to the cervical plate in terms of sagittal alignment reconstruction for 3-level fixation. We recommend applying Zero-P spacers for 3-level ACDF in patients with good preoperative cervical lordosis (C2-7 Cobb angle > 10°), in order to restore and maintain physiological curvature of the cervical spine postoperatively.

Risk Factors for Dysphagia after Anterior Cervical Discectomy and Fusion with the Zero-P implant system: A Study with Minimum of 2 Years Follow-up.

OBJECTIVE: To evaluate the risk factors for dysphagia after anterior cervical discectomy and fusion (ACDF) with the Zero-P Implant System by multidimensional analysis and investigated the predictive values of these risk factors for dysphagia. METHODS: A retrospective analysis of 260 patients who underwent ACDF with the Zero-P Implant System and had at least 2 year of follow-up were performed. All patients were divided into a non-dysphagia group and a dysphagia group. Sex, age, body mass index (BMI), intraoperative time, estimated blood loss, diabetes mellitus, hypertension, smoking, alcohol consumption, prevertebral soft-tissue thickness, the levels of surgery, O-C2 angle, C2-7 angle, T1 slope and segmental angle were analyzed. The Modified Japanese Orthopaedic Association (JOA) scoring system was used to determine functional status. NDI was used to evaluate neck pain and disability. The Bazaz grading system was chosen to evaluate dysphagia after surgery. Postoperative cerebrospinal fluid (CSF) leakage, infection, and dysphagia were recorded in both groups. An independent t-test was used to compare quantitative variables, a chi-square test was used to compare qualitative data between the two groups. To eliminate the influence of confounding factors, logistic regression was performed for multifactor regression of factors. The results were regarded as significant when the P-values were less than 0.05 in this study. RESULTS: In total, the non-dysphagia group comprised 70 patients and the dysphagia group comprised 190 patients, with an average age of 58.33 ± 4.68 years (ranging, 42-82 years). These patients were followed up for 28.5 ± 3.5 months (range, 24-32 months). For clinical outcomes, both groups demonstrated significant improvement in the NDI and JOA scores (P < 0.001). According to the Bazaz dysphagia grading system, mild, moderate, and severe dysphagia were found in 50, 17, and 3 patients, respectively. In total, 37.1% (n = 26) had resolved by 3 month, 38.6% (n = 27) by 6 months, and 17.1% (n = 12) by 12 months. Chi-square test results indicated that number of operated levels, operation time dT1 slope, dO-C2 angle, dC2-7 angle, segmental angle and dPSTT were associated with a high incidence of dysphagia. Multivariate logistic regression analysis showed that number of operated levels, operation time, dC2-7 angle and dPSTT were significantly associated with postoperative dysphagia. CONCLUSIONS: More operated levels, more operation time, more dC2-7 angle and dPSTT were the risk factors for postoperative dysphagia. In additional, sufficient preoperative preparation, evaluation combined with proficient and precise surgical treatment were suggested to reduce the incidence of postoperative dysphagia when ACDF was performed.

A pragmatic single centre retrospective comparative review of complication profile between PEEK cages and Zero-P cage screw constructs.

BACKGROUND: Anterior Decompression and Fusion (ACDF) is a common surgery recommended for symptomatic cervical degenerative disc disease after failed conservative care. There is no consensus on the choice of implants, and it varies between surgeons. This study aims to analyse the early complications following ACDF performed using a standalone cage versus a Zero-P (Cage Screw - (CS)) construct for patients with cervical degenerative disc disease. METHODS: A total of 162 patients underwent an ACDF between August 2016 and July 2018. There were 83 patients (111 cervical disc levels) with standalone cage (SA) and 79 patients (111 cervical disc levels) with cage-screw (CS) fixation. There was no difference between the groups in terms of age, gender, and levels of surgery. The follow-up ranged from 2 months to 24 months. Complications, both clinical and radiological, were assessed between the groups. RESULTS: Both the SA and Zero-P (CS) groups were subdivided into single and multilevel surgery. Complications encountered in the SA group were temporary swallowing problems 10, hoarseness of voice 3, cage migration 1, delayed union 1, Horner's syndrome 1, cage subsidence 2. In the CS group swallowing problems 4, hoarseness of voice 4, CSF leak 1, recurrent symptoms 1. The observed difference in the incidence of complications between the groups did not reach statistical significance. Univariate analysis between the groups did not show any difference in the improvement of cervical sagittal balance, fusion rate, subsidence, and complications encountered. Multivariate logistic regression analysis for complications showed no difference between the groups when assessed for smoking, gender, age, Charlson comorbidity index, levels of surgery, fusion status, Odom score, or the type of implant. CONCLUSION: In this short-term study, the standalone (SA) cages showed no difference in their complication profile in comparison to a cage-screw construct for both single and multilevel ACDF. Standalone cages might be a cost-effective option without increased complication risks. Nevertheless, we propose a longer-term follow-up with a prospective randomized trial for further evaluation of this finding.

Comparison of Patient-Reported Postoperative Dysphagia in Patients Undergoing One-Level Versus Two-Level Anterior Cervical Discectomy and Fusion with the Zero-P Implant System.

To investigate whether dysphagia differs between one-level and two-level anterior cervical discectomy and fusion (ACDF) with the Zero Profile (Zero-P) Implant System. A retrospective analysis of 208 patients who underwent ACDF with the Zero-P Implant System and had at least one year of follow-up was performed from January 2013 to December 2018. The patients were divided into two groups based on the number of operated levels (one-level group, N = 86; two-level group, N = 122). Dysphagia was assessed based on the Bazaz grading system. The incidence of dysphagia and the severity of dysphagia at each follow-up were compared between the two groups. The patients were divided into two groups (nondysphagia group, N = 160; dysphagia group, N = 48), and covariates were obtained for multivariate analysis, including demographic parameters, surgical parameters, and radiographic parameters. The results showed that the incidence and severity of postoperative dysphagia in the two-level group were significantly greater at 1 week, 1 month and 3 months postoperatively than those in the one-level group. The results of ordinal logistic regression showed that older age, two-level surgery, greater prevertebral soft tissue swelling (PSTS) and the difference between the postoperative and preoperative C2-7 angle (dC2-7A) were significantly associated with a higher incidence of dysphagia after ACDF with the Zero-P. Two-level ACDF with the Zero-P can result in a significantly greater incidence and severity of transient postoperative dysphagia. Older age, greater PSTS and the dC2-7A were also associated with postoperative dysphagia after ACDF with the Zero-P.

The effect of the difference in C2-7 angle on the occurrence of dysphagia after anterior cervical discectomy and fusion with the zero-P implant system.

OBJECTIVES: To investigate the effect of the difference in C2-7 angle on dysphagia after anterior cervical discectomy and fusion (ACDF) with the Zero-P Implant System. METHODS: A retrospective analysis of 181 patients who underwent ACDF with the Zero-P Implant System and had at least one year of follow-up from January 2011 to November 2018 was performed. All patients were divided into a non-dysphagia group and a dysphagia group to explore the effect of the difference between postoperative and preoperative C2-7 angle (dC2-7A) on postoperative dysphagia. At the same time, other possible related factors including the difference between postoperative and preoperative O-C2 angle (dO-C2A), sex, age, body mass index (BMI), intraoperative time, estimated blood loss, diabetes mellitus, hypertension, smoking, alcohol consumption, prevertebral soft-tissue swelling (PSTS), the highest segment involved in the surgery and the levels of surgery segments were analyzed. RESULTS: In total, the non-dysphagia group comprised 139 patients and the dysphagia group comprised 42 patients. The single-factor analysis showed that smoking, PSTS and dC2-7A were significantly different between the two groups (P < 0.05). Spearman's correlation coefficient showed no significant correlation between the degree of dysphagia and dC2-7A (P > 0.05). The results of the multiple-factor analysis with an ordinal logistic regression model showed that smoking, PSTS and dC2-7A were significantly associated with the incidence of dysphagia (P < 0.05). CONCLUSIONS: The postoperative C2-7 angle has an important effect on the occurrence of dysphagia in patients undergoing Zero-P implant system interbody fusion surgery.

Improved Dysphagia Outcomes in Anchored Spacers Versus Plate-Screw Systems in Anterior Cervical Discectomy and Fusion: A Systematic Review.

STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVE: To perform a systematic review of clinical outcomes between stand-alone anchored spacers and traditional cages with plate fixation for dysphagia and pseudoarthrosis using data from clinical trials. METHODS: Our search protocol was added to PROSPERO register and systematic review using PRISMA method was performed. Then, we systematically searched for studies addressing stand-alone anchored spacers in patients who underwent ACDF. Mean Neck Disability Index (NDI), dysphagia incidence % (Dinc%), and Swallowing-Quality of Life (SQOL) scores during preoperative, immediate postoperative and last follow-up visits were extracted. Chi-square and analysis of variance (ANOVA) tests were used for statistical comparisons (P ≤ .05). RESULTS: The initial search generated 506 articles in CENTRAL and 40 articles in MEDLINE. Finally, 14 articles were included. Total number of patients was 1173 (583 anchored stand-alone and 590 plate). Dinc% scores were statistically significantly lower in the stand-alone anchored spacer compared to the plate-screw construct (P ≤ .05). ANOVA showed no statistically significant difference in the comparisons of SQOL. On the other hand, NDI scores were statistically significantly lower in baseline of stand-alone anchored spacer and the plate-screw construct compared with both immediate postoperative and last follow-up visits (P ≤ .05). CONCLUSIONS: Our study results revealed that the stand-alone anchored spacers were associated with less dysphagia in the immediate and last follow-up.

Comparison between anterior cervical discectomy and fusion using zero-P and traditional anterior cervical plate plus cage for treating two-level cervical spondylosis / 中国组织工程研究

BACKGROUND: Anterior cervical discectomy and fusion is a classic surgical procedure for the treatment of cervical spondylosis. At present, we can use a Zero-P interbody fusion fixture and a traditional cervical anterior plate plus cage as an internal fixation material. The Zero-P has less postoperative esophageal interference and lower incidence of postoperative dysphagia compared with traditional anterior cervical plate fixation. Besides, the Zero-P could avoid the risk of excessively long or pooriy placed plate injury to adjacent segmental intervertebral discs. OBJECTIVE: To compare the safety and effectiveness between two-level anterior cervical discectomy and fusion using Zero-P and using traditional anterior cervical plate plus cage. METHODS: Clinical data of sixty patients who underwent two-level anterior cervical discectomy and fusion in the Chengdu Third People’s Hospital from May 2016 to May 2018 were retrospectively analyzed. The patients were divided into Zero-P group (Zero-P fusion, n=30) and plate group (anterior cervical plate fixation combined with cage implantation, n=30). All patients in the two groups had informed consent to the treatment plan. This study was approved by the hospital ethics committee. The Japanese orthopedic association score, neck disability index score and Bazaz swallowing function score were used to evaluate the clinical efficacy. Cervical X-ray and cervical CT scans were performed to assess cervical curvature, observe bone graft fusion, and implant displacement, loosening and breakage. RESULTS AND CONCLUSION: (1) All surgeries were successfully completed in 60 patients. The wounds healed in stage I after operation. There were no serious complications such as nerve injury, esophageal fistula, and cerebrospinal fluid leakage. (2) During the follow-up, there was no significant difference in neck disability index, Japanese orthopedic association score and bone graft fusion rates between the two groups (P > 0.05). (3) The incidence and severity of dysphagia in the Zero-P group were lower than those in the plate group at various time points after operation (all P < 0.05). (4) The overall curvature and operative segments curvature were better in the plate group than in the Zero-P group 6 months after surgery and in final follow-up (P < 0.05). (5) Two-level anterior cervical discectomy and fusion using Zero-P is a safe and effective operative method. The operation time, bleeding volume, number of fluoroscopy and postoperative dysphagia incidence were better than the traditional anterior cervical plate plus cage fixation system, but it is not as good as the traditional anterior cervical plate plus cage system in the curvature of the cervical spine. Zero-P is not recommended for patients with obvious abnormal cervical curvature before operation.

A Comparison of Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion in Patients with Two-Level Cervical Degenerative Disc Disease: 5-Year Follow-Up Results.

OBJECTIVE: To present a long-term clinical and radiographic comparison between the Prestige LP cervical disc replacement and the Zero-P spacer cervical disc fusion in the treatment of patients with symptomatic 2-level cervical degenerative disease. METHODS: In total, 36 patients in the anterior cervical discectomy and fusion (ACDF) group and 24 patients in the cervical disc arthroplasty (CDA) group were analyzed before surgery and at 1 week and 3, 6, 12, 24, and 60 months after surgery. Clinical assessments included the Japanese Orthopaedic Association score, visual analog scale, and Neck Disability Index scores. Radiographic assessments included cervical lordosis, range of motion (ROM) of the total cervical spine, functional spinal unit (FSU), and superior and inferior adjacent segments. Complications including heterotopic ossification and adjacent-segment degeneration (ASD) at 5-year follow-up were collected as well. RESULTS: Mean follow-up period was 65.6 months. Both the ACDF and CDA groups showed significant clinical improvements in terms of Japanese Orthopaedic Association score, visual analog scale, and Neck Disability Index (P < 0.05), but there was no significant difference between groups at the last follow-up period. A significant increase of cervical lordosis was observed in the CDA group after surgery whereas a significant difference was not observed between groups. ROM of the total cervical spine and FSU were maintained during the follow-up, and a significant decrease was observed in the ACDF group after surgery (P < 0.05). The ROM of the superior adjacent segment did not show any difference whereas the ROM of the inferior adjacent segment in the ACDF group presented a significant increase at 6 months and 1 year after surgery and a significant decrease at the last follow-up period. A total of 8 (33.3%) patients in the CDA group had an occurrence of heterotopic ossification. ASD was observed in 2 (8.3%) patients who underwent CDA surgery and 8 (22.2%) patients who underwent ACDF surgery. CONCLUSIONS: The use of the Prestige-LP and ZERO-P Spacer implantations is safe and effective. At 5 years after surgery, CDA with Prestige-LP is superior in terms of ROM of the total cervical spine, FSU, and inferior adjacent segment. It also has a relatively low occurrence rate of ASD. This procedure may be a suitable choice for the treatment of contiguous 2-level CDDD.

Comparison between zero-profile spacer and plate with cage in the treatment of single level cervical spondylosis.

BACKGROUND: Retrospective study of 68 patients of symptomatic cervical spondylosis who were treated by anterior cervical discectomy and fusion (ACDF). OBJECTIVE: The purpose of this study was to compare the clinical and radiological outcomes of patients with single level cervical spondylosis using either zero-profile spacer (group A) or anterior cervical plate and cage (group B). METHODS: Clinical and radiological data of 68 patients undergoing ACDF from C3-C7 were collected retrospectively. There were 35 patients with a mean age of 54.05 years who received treatment by zero-profile implant. A total of 33 patients with a mean age of 52.09 years underwent fusion by traditional plate with cage. Group A and group B were followed up for an average of 23.68 months and 24.39 months, respectively. Age, blood loss, and operation time were assessed. The clinical outcomes were evaluated by JOA and VAS score before and after surgery. In addition, incidence of dysphagia was recorded. The Cobb angle (from C2 to C7) change was measured on the lateral cervical spine radiographs. RESULTS: There was no significant difference in terms of operation time and blood loss between two groups. The postoperative JOA significantly increased and the VAS decreased correspondently in both groups. The postoperative Cobb angle increased and showed statistical difference compared with preoperative Cobb angle in both groups. There was no significant difference between group A and group B in achieving clinical symptoms and radiograph improvement according to postoperative JOA, VAS and Cobb angle comparison. The incidence of postoperative dysphagia was lower in the group A than group B. CONCLUSIONS: Our study suggests that the application of zero-p spacer can achieve similar clinical and radiological improvement compared with traditional plate and cage. Meanwhile, zero-p is superior to plate and cage with a lower incidence of postoperative dysphagia.

Phylogenetically Conserved Sequences Around Myelin P0 Stop Codon are Essential for Translational Readthrough to Produce L-MPZ.

Myelin protein zero (P0, MPZ) is the main cell adhesion molecule in peripheral myelin, the sequence of which is evolutionarily highly conserved. Large myelin protein zero (L-MPZ) is a novel translational readthrough molecule in mammals in a physiological status and is encoded by the P0 mRNA with an extra domain. The sequence similarities in the L-MPZ-specific region are found in humans and frogs but not in fish P0 cDNA. Actual synthesis of L-MPZ has been detected in rat and mouse sciatic nerve but not yet evaluated in frogs and humans. The production mechanism and physiological functions of L-MPZ remain unknown. Additionally, the sequence context around the canonical stop codon is significant for readthrough in viruses and yeast, but the correlation between the sequence around P0 stop codon and L-MPZ synthesis is unclear. Here, we focused on the phylogenetic pathways in L-MPZ synthesis. We have shown that L-MPZ is widely produced from frogs to humans using western blotting against L-MPZ. Mutation analysis of the sequence around the stop codon for L-MPZ synthesis using a mammalian in vitro transcription/translation system revealed that the evolutionarily conserved sequence around P0 stop codon is susceptible to readthrough and is similar to the consensus motif in viruses and yeast UAG stop codon type molecules. Our results demonstrate that the phylogenetically conserved sequence around the canonical P0 stop codon is essential for L-MPZ synthesis, suggesting that phylogenetic emergence of L-MPZ in amphibians may be related to particular distribution and/or function in the PNS myelin.

Comparison of prevertebral soft tissue swelling and dysphagia between Zero-p and traditional cage and titanium plate for anterior cervical discectomy with fusion / 局解手术学杂志

Objective To explore the relationship among the prevertebral soft tissue swelling and dysphagia rate after anterior cervical diskectomy and fusion(ACDF),and to investigate the prevertebral soft tissue swelling and dysphagia rate after Zero-p or traditionaI cage and titanium plate for one-level lesion of cervical myelopathy.Methods The clinical data of 54 patients with one-level lesion (C5/6) of cervical myelopathy who undelwent anterior cenrical discectomy and fusion by Zero-p (n =25) or traditional cage and titanium plate (n =29) were analyzed.The postoperative prevertebral soft tissue swelling was measured by lateral radiographs.Patients were divided into the swelling group (n =24) and the non-swelling group(n =30) based on the degree of prevertebral soft tissue swelling and the incidences of dysphagia were analyzed.Patients were divided into the Zero-p group (n =25)and the Cage group (n =29) based on surgical treatment,the postoperative prevertebral soft tissue swelling and dysphagia rate were compared.Results The rate of dysphagia in swelling group was 45.8％,which was higher than 13.3％ in non-swelling group,the difference was significant(P ＜0.05).The postoperative prevertebral soft tissue swelling was 6.22 mm averagely after Zreo-p,which was less than that after traditional cage and titanium plate for anterior cervical discectomy with fusion(9.25 mm),the difference was significant (P ＜ 0.05).The incidence of dysphagia in Zero-p group was 12％,which was lower than 41.4％ in Cage group,and the difference was statistically significant (P ＜ 0.05).Conclusion It is a clinical significance to evaluate the degree of prevertebral soft tissue swelling by cervical lateral X-ray after ACDF,when the degree of prevertebral soft tissue swelling is greater,the incidence of complications such as dysphagia is higher.In addition,The Zero-p for the treatment of single one-level lesion of cervical myelopathy(C5/6) has a lower degree of prevertebral soft tissue swelling and dysphagia rate than the traditional Cage and titanium plate fusion.

Use of a Zero-Profile Device for Contiguous 2-Level Anterior Cervical Diskectomy and Fusion: Comparison with Cage with Plate Construct.

BACKGROUND: A new zero-profile, standalone device (Zero P) was recently developed and has shown a lower incidence rate of complications and competitive clinical outcomes compared with anterior cervical cage with plate construct (CP) in single and multilevel anterior cervical diskectomy and fusion (ACDF). However, there is still concern whether Zero P is appropriate for multilevel ACDF. In addition, there have been few reports of contiguous 2-level ACDF used in conjunction with Zero P. METHODS: We reviewed contiguous 2-level ACDF performed from December 2006 to February 2015. A total of 63 patients met inclusion criteria for the study (CP group = 32 cases; Zero P group = 31 cases). All preoperative and postoperative clinical and radiologic parameters were recorded. These parameters were compared between both groups. RESULTS: The postoperative change of Cobb S over time in the Zero P group was significantly different from that in the CP group. The maintenance of Cobb S in the Zero P group was better than that in the CP group (P < 0.05). The maintenance of anterior intervertebral disk height (IDH) at postoperative assessment for the Zero P group was significantly better than that in the CP group (P < 0.05). Within-group comparison of the postoperative change of anterior and posterior IDH over time revealed that the anterior IDH was significantly lower than the posterior IDH in the Zero P group (P < 0.05). CONCLUSION: For 2-level contiguous ACDF, the use of a zero-profile device has the capacity to show compatible outcomes in correction and maintenance of segmental angle if the anterior titanium alloy plate is properly positioned at the anterior vertebral line.

The new Zero-P implant can effectively reduce the risk of postoperative dysphagia and complications compared with the traditional anterior cage and plate: a systematic review and meta-analysis.

BACKGROUND: The low-profile angle-stable spacer Zero-P is a new kind of cervical fusion system that is claimed to limit the potential drawbacks and complications. The purpose of this meta-analysis was to compare the clinical and radiological results of the new Zero-P implant with those of the traditional anterior cage and plate in the treatment of symptomatic cervical spondylosis, and provides clinicians with evidence on which to base their clinical decision making. METHODS: The following electronic databases were searched: PMedline, PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, Evidence Based Medicine Reviews, VIP, and CNKI. Conference posters and abstracts were also electronically searched. The efficacy was evaluated in intraoperative time, intraoperative blood loss, fusion rate and dysphagia. RESULTS: For intraoperative time and intraoperative blood loss, the meta-analysis revealed that the Zero-P surgical technique is not superior to the cage and plate technique . For fusion rate, the two techniques both had good bone fusion, however, this difference is not statistically significant. For decrease of JOA and dysphagia, the pooled data showed that the Zero-P surgical technique is superior to the cage and plate technique. CONCLUSIONS: Zero-P interbody fusion can attain good clinical efficacy and a satisfactory fusion rate in the treatment of symptomatic cervical spondylosis. It also can effectively reduce the risk of postoperative dysphagia and its complications. However, owing to the lack of long-term follow-up, its long-term efficacy remains unknown.

Comparison of anterior cervical discectomy and fusion with the zero-profile device versus plate and cage in treating cervical degenerative disc disease: A meta-analysis.

Zero-profile device was applied to diminish the irritation of the esophagus in the treatment of cervical degenerative disc disease. However, the clinical application of the zero-profile device has not been testified with clinical evidence. The aim of the meta-analysis was to systematically compare the safety and effectiveness of anterior cervical discectomy and fusion with zero-profile device with plate and cage for the treatment of cervical degenerative disc disease. Electronic searches of PubMed and Embase were conducted up to May 2015. Relevant studies were included. Weighted mean difference (WMD) and 95% confidence intervals (CI) were assessed for continuous data. Risk ratio (RR) and 95% CI were assessed for dichotomous data. P value <0.05 was considered to be significant. Eleven studies were included in the meta-analysis. Compared with plate and cage, zero-p is associated with lower operation time of two-level surgery, less intraoperative blood loss, higher subsidence rate, higher JOA score, lower incidence of dysphagia in short-term (RR: 0.72, 95% CI [0.58, 0.90], P=0.005, I2=22%) and long-term (RR: 0.12, 95% CI [0.05, 0.30], P<0.00001, I2=0%) and lower Cobb angle of multilevel surgery (WMD: -3.16, 95% CI: [-4.35, -1.97], P<0.00001, I2=0%). No significant difference was found in one-level and two-level Cobb angle, fusion rate and operation time of one-level and three-level surgery. Both zero-p implantation and the plate and cage have respective advantages and disadvantages.

Comparative analysis of clinical outcomes between zero-profile implant and cages with plate fixation in treating multilevel cervical spondilotic myelopathy: A three-year follow-up.

OBJECTIVES: This study aimed to figure out three-year clinical outcomes and complications of ACDF with Zero-p in treating multilevel cervical spondylotic myelopathy (MCSM) by comparing with plate fixation. CLINICAL MATERIALS AND METHODS: Patients with MCSM caused by degenerative disc herniation only were recruited from April 2010 to December 2010. According to the surgical procedures, the patients were divided into two groups at random, the plate group and Zero-P group. The data was collected before surgery and at three-year follow-up. Clinical parameters, including Japanese orthopedic association (JOA) score, neck disabled index (NDI) were evaluated. Cervical segmental lordosis was calculated and fusion in each level was assessed on lateral radiographs. The Bazaz's criterion and the short Swallowing and Quality of Life (SQOL) questionnaires were used to evaluate the dysphagia incidence and severity respectively. The presence of ALOD was observed and recorded on lateral radiographs. RESULTS: A total of 72 patients (46 men and 26 women) were recruited. The mean age at operation was 52.9±7.9years, ranged from 43 to 69 years. There was no significant difference between two groups preoperatively in age, sex, operative levels, JOA, NDI, cervical lordosis, dysphagia incidence, SQOL and ALOD incidence. JOA, NDI and cervical lordosis improved postoperatively and postoperative SQOL got restitution in both groups. However, no difference was detected. There were 7 patients with ALOD in the plate group after surgeries while there was only 1 patient in Zero-P group. The difference of AOLD incidence between them was significant. Of the 7 patients with ALOD in the plate group, 4 patients developed ALOD in cranial level, 2 in caudal level and 1 in both levels. The patient in Zero-P group developed ALOD in caudal level. CONCLUSION: Based on the three-year follow-up, we could not conclude that Zero-P was superior to plate fixation in clinical outcomes such as neurological results, cervical lordosis, fusion rate and the incidence and severity of dysphagia in treating MCSM. However, it had the advantage of reducing ALOD incidence which tended to happen in ACDF with plate fixation.